1. Field of the Invention
The invention is based on a fuel injection valve for internal combustion engines particularly as a component of a reservoir fuel injection system.
2. Description of the Prior Art
A fuel injection valve of the type with which this invention is concerned is known from the literature, see the document Dieselmotorentechnik 2000 [Diesel Motor Engineering 2000], Expert Verlag 1999, p. 222. This fuel injection valve is a component of a reservoir fuel injection system. The fuel injection valve has a valve body and an injection valve member guided so that it can move axially, which controls at least one injection opening. The injection valve member has a pressure shoulder that defines a pressure chamber; the pressure chamber is supplied with pressurized fuel from a high-pressure fuel source as a result of which the injection valve member can be lifted up from a valve seat counter to a closing force in order to open the at least one injection opening. The fuel injection valve has an electric control valve which influences the movement of the injection valve member by controlling the pressure which prevails in a control pressure chamber connected to the high-pressure fuel source and acts on the injection valve member at least indirectly in its closing direction; the control valve can connect the control pressure chamber to a discharge chamber. Inside a sleeve-shaped section of an insert piece inserted into the valve body, the control pressure chamber is defined by a section of the injection valve member or an intermediary member that acts on it. An annular chamber is formed between the valve body and the sleeve-shaped section of the insert piece. The insert piece has a flange with which it contacts the valve body toward the annular chamber, in the direction of the longitudinal axis of the valve body. The control pressure chamber in the sleeve-shaped section of the insert piece communicates with the annular chamber via at least one opening in the insert piece. An inlet bore is provided in the valve body and this bore extends at least essentially in the longitudinal direction of the valve body and connects the pressure chamber to a connection of the high-pressure fuel source that is provided on the fuel injection valve. The annular chamber is connected to the inlet bore by means of a connecting bore provided in the valve body. The connecting bore extends approximately at right angles to or inclined at an acute angle to the inlet bore and connects to the circumferential surface of the annular chamber. The connecting bore intersects the inlet bore in a region disposed at the level of the annular chamber. At the intersection of the connecting bore and the inlet bore, very high mechanical stresses occur in the valve body, induced by the high pressure prevailing in the annular chamber and the bores and by the bracing of the insert piece to the valve body. In order to achieve a sufficient service life of the valve body, the fuel pressure must be limited and/or an expensive, high-strength material must be used. In order to comply with current and future emissions limits, however, the goal is to increase fuel pressure further.
The fuel injection valve according to the invention has the advantage over the prior art that the mechanical stresses in the valve body at the intersection of the connecting bore and the inlet bore are reduced and as a result, the fuel pressure can be increased and/or less expensive, lower-strength materials can be used and a sufficient service life of the valve body is nevertheless assured.
One embodiment of the fuel injection valve according to the invention permits a level disposition of the connecting bore with a slight inclination in relation to the inlet bore.